The diameter you have is the same as the excav in the video. That excav is quicker than earlier Stahl hoes I had b/c it's using 2mm plumbing, the earlier ones were 1,5mm ID. That extra 0,5mm in dia made a notable difference in cycle speed.
Increasing the pressure will make it flow faster too forcing the oil through the lines quicker. But if you are putting this into a plastic Bruder model, the arm/pivot points will break.
My 850 uses a 0,3ml/revolution Jung pump and it's capable of 1200ml/min. The cyl bores are 20mm (boom/bucket) & 22mm (stick), all four cyls filling from the bottom of cyl at once makes the overall speed quite slow with 2,5mm ID hoses.
Premacon's 944 excav uses a Jung pump, maybe the 0,3/rev with I'm assuming 14mm bores, the cyls move way too quick making the model unrealistically fast & the operators spill dirt everywhere, hit the trks, ect. Proper radio programming could prevent a lot of that with much finer control on the tx sticks.
